From 9cc93a1c82bf1d1c12fb0e8d933ef12cecc37540 Mon Sep 17 00:00:00 2001
From: Joshua Terranova <terranovajoshua1@gmail.com>
Date: Mon, 10 Aug 2026 18:22:12 -0700
Subject: [PATCH] BUG: stop dict_generator from sampling initial_solution
 (#1109)

Generate stochastic samples from declared constructor inputs only, and
validate StochasticFlight.initial_solution on construct.
---
 rocketpy/stochastic/stochastic_flight.py      |  1 +
 rocketpy/stochastic/stochastic_model.py       | 10 +++++--
 .../unit/stochastic/test_stochastic_flight.py | 26 +++++++++++++++++++
 3 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/rocketpy/stochastic/stochastic_flight.py b/rocketpy/stochastic/stochastic_flight.py
index 525526798..85187e286 100644
--- a/rocketpy/stochastic/stochastic_flight.py
+++ b/rocketpy/stochastic/stochastic_flight.py
@@ -94,6 +94,7 @@ def __init__(
             heading=heading,
         )
 
+        self._validate_initial_solution(initial_solution)
         self.initial_solution = initial_solution
         self.terminate_on_apogee = terminate_on_apogee
         if max_time is None:
diff --git a/rocketpy/stochastic/stochastic_model.py b/rocketpy/stochastic/stochastic_model.py
index be2438a0c..d73bf07f8 100644
--- a/rocketpy/stochastic/stochastic_model.py
+++ b/rocketpy/stochastic/stochastic_model.py
@@ -621,13 +621,19 @@ def dict_generator(self):
 
         Notes
         -----
-        1. The dictionary is generated by iterating over the class attributes and:
+        1. The dictionary is generated by iterating over the *declared*
+           stochastic inputs (constructor kwargs), not every attribute on
+           ``self``. This avoids treating opaque tuples such as
+           ``initial_solution`` as ``(nominal, spread, sampler)`` triples.
             a. If the attribute is a tuple, the value is generated using the\
                 distribution function specified in the tuple.
             b. If the attribute is a list, the value is randomly chosen from the list.
         """
         generated_dict = {}
-        for arg, value in self.__dict__.items():
+        for arg in self.__stochastic_dict:
+            if not hasattr(self, arg):
+                continue
+            value = getattr(self, arg)
             if isinstance(value, tuple):
                 dist_sampler = value[-1]
                 generated_dict[arg] = dist_sampler(value[0], value[1])
diff --git a/tests/unit/stochastic/test_stochastic_flight.py b/tests/unit/stochastic/test_stochastic_flight.py
index e03917475..233800701 100644
--- a/tests/unit/stochastic/test_stochastic_flight.py
+++ b/tests/unit/stochastic/test_stochastic_flight.py
@@ -45,3 +45,29 @@ def test_stochastic_flight_optional_attributes(flight_calisto_robust):
     assert obj.terminate_on_apogee is True
     assert obj.time_overshoot is True
     assert obj.max_time == 987.6
+
+
+def test_dict_generator_skips_initial_solution_tuple(flight_calisto_robust):
+    """Regression for #1109: tuple initial_solution must not be sampled."""
+    initial_solution = tuple(float(i) for i in range(14))
+    stochastic_flight = StochasticFlight(
+        flight=flight_calisto_robust,
+        initial_solution=initial_solution,
+        rail_length=(5.2, 0.1),
+    )
+    generated = next(stochastic_flight.dict_generator())
+    assert "initial_solution" not in generated
+    assert stochastic_flight.initial_solution == initial_solution
+
+
+def test_dict_generator_skips_initial_solution_list(flight_calisto_robust):
+    """List-form initial_solution must not be randomly subset-sampled."""
+    initial_solution = [float(i) for i in range(14)]
+    stochastic_flight = StochasticFlight(
+        flight=flight_calisto_robust,
+        initial_solution=initial_solution,
+        inclination=[85, 86, 87],
+    )
+    generated = next(stochastic_flight.dict_generator())
+    assert "initial_solution" not in generated
+    assert stochastic_flight.initial_solution == initial_solution